Spar buoy pen system

ABSTRACT

A spar buoy pen system formed of a net pen, vertical spar buoys, and anchors. The spar buoys are formed of elongate tubular columns having a center of ballet above the center of gravity to float in a substantially upright position. Anchor lines, auxiliary floats, and attachment lines deflect the spar buoys at a predetermined angle such that the spar buoys and the anchors cooperate to hold the net pen in a predetermined configuration and in a taut condition. Alternative versions of the system may be provided with damper plates that are attached to the spar buoys so as to limit their wave-induced motions. A predator net can also be attached to the system to protect the net pen and its contents.

This application is a continuation-in-part of U.S. patent applicationSet. No. 07/339,676 filed Apr. 18, 1989 now U.S. Pat. No. 5,007,376.

TECHNICAL FIELD

The present invention pertains to net pens for growing fish, othermarine life and organisms and, more particularly, to a spar buoy pensystem for use in open waters.

BACKGROUND

Fish pens are generally constructed of fish netting that is formed tohave a closed bottom, closed sides, and an open or closed top. Ahorizontal floating frame structure that lies flat On the ocean surfaceis used to shape the netting and provide a working platform. Weights arehung from the netting to provide draft and shape for the pen. Althoughthese horizontal frame systems have been generally suitable for theirpurposes, they have several drawbacks.

When used in closed or protected waters, horizontal frame systems arevisually objectionable, are inefficient in the use of pen volume, andtend to accumulate waste that pollutes the aquatic environment. Whileuse of the pen system in open waters will avoid this pollution, thehorizontal frame systems currently in use with these pen systems are notusable in open waters because of the roughness of the water and theunsteadiness of current flow. In particular, the surface-supportedhorizontal frames respond to passing waves with violent motions that cancause extreme stress on the structural components of the frame.Furthermore, the use of weights to shape the pen vertically is notcompatible with the open water because water currents can move theweights, thus reducing the usable volume of the pen. In other words, theweights become less effective as current increases. As a result, thefloating frame pen systems using suspended weights are limited toshallow, vertical configurations that can only be used in closed orprotected waters where strong currents and wave conditions are notpresent. Hence, there is a need for a floating pen system that is stableenough to maintain a workable configuration without undue stress inlarge bodies of open water or bodies of water where strong currents arepresent.

SUMMARY OF THE INVENTION

The present invention is directed to spar buoy pen system for holding apen in a predetermined configuration in an open body of water. The pensystem comprises a flexible wall member that restricts movement of waterand/or marine life to a predetermined area. The system further includesat least one, and preferably a plurality of elongate buoyancy members,preferably having a tubular shape, that are attached to the flexiblewall to float in a substantially upright position. Anchors are attachedto each of the elongate buoyancy members to hold the elongate buoyancymembers at a fixed location in the open body of water such that theflexible wall is held in a taut condition in a predeterminedconfiguration.

In accordance with another aspect of the present invention, auxiliaryfloats are attached to the anchor lines between each anchor and eachelongate buoyancy member to provide an upward force to the anchor linesto urge the elongate buoyancy member laterally outward from the flexiblewall to maintain the flexible wall in a taut condition.

In accordance with another aspect of the present invention, the elongatebuoyancy members are further attached to each other such that, uponremoval of the flexible wall, the elongate buoyancy members willmaintain their positions in the predetermined configuration.

In accordance with yet another aspect of the present invention, theelongate buoyancy members are displaced from the upright position at apredetermined angle. This predetermined angle is in the range of 5° to25° fro the vertical, and preferably is 15° from the vertical.

In accordance with still yet another aspect of the present invention,the flexible wall may comprise either a net having a mesh of apredetermined size, a fabric cloth, or a combination of these differentmaterials that permits a limited flowthrough of liquid.

.Iadd.As will be readily appreciated from the foregoing description, thespar buoy pen system makes it possible to use a net pen aquaculturesystem in open and unprotected waters. The spar buoy as a floatingvertical column has a draft much greater than its beam or depth. As aresult of its shape and small waterplane area, the spar buoy is"transparent" to prevailing wave spectra, thus minimizing wave-inducedmotions. In addition, the compressive strength of the spars fixes thedepth of the net pen to a predetermined value, which is independent ofprevailing current strength. Finally, because of their stability andcompressive strength, the spar buoys can be used to house auxiliaryequipment, or extensions can be added above the buoys for bird nets,etc. The system is easily constructed, maintained, and relocated, plusit easily accommodates pens of a variety of shapes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a spar buoy pen formed in accordance withthe present invention.

FIG. 2 is an isometric view showing an alternative embodiment of thespar buoy pen system including a predator net and damper plates attachedto the spar buoys.

FIG. 3 is a view of an alternative stacked damper plate arrangement foruse with the present invention.

.[.As will be readily appreciated from the foregoing description, thespar buoy pen system makes it possible to use a net pen aquaculturesystem in open and unprotected waters. The spar buoy as a floatingvertical column has a draft much greater than its beam or depth. As aresult of its shape and small waterplane area, the spar buoy is"transparent" to prevailing wave spectra, thus minimizing wave-inducedmotions. In addition, the compressive strength of the spars fixed thedepth of the net pen to a predetermined value, which is independent.].

.Iadd.DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a representative embodiment of the spar buoy pensystem 10 situated in a body of water 12. The spar buoy pen system 10includes a net pen 14, a plurality of elongate buoyancy members, in thiscase spar buoys 16 attached to the net pen 14, and anchors 18 resting onthe sea floor 20. Each spar buoy 16 has an anchor 18 attached to it withan anchor line 22. An auxiliary float 24 is attached to each anchor line22.

The net pen 14 is formed from six generally vertically oriented flexiblewalls 26 and an attached flexible bottom 28. The flexible walls 26 andbottom 28 are constructed of netting material having a mesh sizeselected to restrict desired marine life or marine organisms within thenet pen 14. Because fish tend to swim together in large groups, the wall26 taper inward at the bottom 28 to eliminate dead space and makeefficient use of the volume within the net pen 14. The net pen 14 has norigid structure in itself, relying on the attached spar buoys 16 andanchors 18 to maintain the hexagonal configuration in a taut condition.Although the representative embodiment illustrates the net pen 14 beingformed of netting, a fabric-like nylon or canvas could be used ifdesired.

The spar buoys 16 are elongate tubular columns that may be formed fromstell pipe or plastic. The top and bottom are capped to provide atotally enclosed watertight chamber within each buoy 16, creatingbuoyancy. Flotation device may be used with the buoys 16 to provideadditional buoyancy. In addition, ballasts in the form of some type ofweight must be added near the bottom.Iaddend. of each spar buoy 16. Inorder for the invention to properly function, it is critical that thecenter of buoyancy be above the center of gravity in each spar buoy 16so that the buoy 16 will float in a substantially upright position. Themount of flotation and ballast used on each buoy will vary, depending onwhether the buoy is to be used fully submerged or whether a portion ofthe buoy is to remain above the waterline. In the representativeembodiment illustrated in FIG. 1, the waterline 30 is denoted by adarkened ring around the net pen 14.

Each spar buoy 16 is attached to the net pen 14 with an attachment line32 at the top and bottom of the buoy 16. In addition, connecting lines34 attach the spar buoys 16 to each other at their tops and bottoms.While not critical to practicing the present invention, these connectinglines 34 will maintain the spar buoy 16 in their predeterminedconfiguration, in this ease, the hexagonal shape, even when the net pen14 is removed. This is to facilitate removal and replacement of the netpen 14 in the open water without having to remove or replace the sparbuoys 16.

Each spar buoy 16 is anchored at a predetermined location to the seafloor 20 by an anchor 18. The anchor may be any suitable weightedarticle that will remain stationary when placed on the sea floor 20. Theanchor lines 22 are shown attached to each buoy 16 at one or morepoints, and preferably at two locations to stabilize the buoy 16 in thewater. To avoid a downward pull on the buoys from the anchor lines 22,an auxiliary float 24 is attached to each anchor line 22 to provide anupward force on the anchor line 22. This results in the anchor line 22exerting a lateral force on each buoy 16 to urge each spar buoy 16laterally outwardly from the net pen 14 to thereby maintain the net pen14 in a taut, or stretched, open state.

Although the spar buoy 16 may be used in a substantially uprightposition, this may be too flexible in some systems. It has been foundthat if the spar buoys are deflected from the vertical, they will reacha point where they are resistant to further deflection because ofincreased righting moment. Depending on the configuration of theparticular spar buoy, this angle has been found to be in the range of 5°to 25°, and, in the representative embodiment shown in FIG. 1, ispreferably 15°. Consequently, the anchors 18 and the deflected sparbuoys 16 cooperate to hold the net pen 14 in the hexagonal configurationand in a taut condition. To assist in maintaining the spar buoys 16 atan angle, the attachment lines 32 at the top of each buoy 16 are shorterthan the attachment lines 32 at the bottom of each buoy 16, and theanchor lines 22 are attached preferably below the midpoint of each sparbuoy 16.

An alternative spar pen system 40 of this invention is described withrespect to FIG. 2. The spar pen system 40 includes the same basic netpen 14, spar buoys 16, anchors 18 and float 24 included in the previousembodiment of the invention. Attached to the bottom of each spar buoy 16is a damper plate 42. The damper plates 42 are attached to theassociated spar buoys 16 by a set of lines 44 (three shown) so that thedamper plates are suspended in substantially horizontal orientation. Thedamper plates 42, which reduce the vertical motion of the spar buoys 16,have a mass and a diameter which are a function of the extent to whichthey are required to reduce vertical motion and the size of theassociated spar buoys 16. The damper plates 42 typically range indiameter from 4 to 12 feet and in mass from 200 to 10,000 pounds. Thelines 44 are designed to suspend the damper plates 42 anywhere from 3 to16 feet below the associated spar buoys 16. For example, a spar pensystem provided with 40-foot spar buoys 16 may be provided with damperplates 42 that are approximately 6 to 7 feet across, weigh approximately4,000 pounds, and that are suspended approximately 12 feet below theassociated spar buoys.

Spar buoy pen 40 is also provided with a predator net 46 that issuspended between the spar buoys 16. In the illustrated embodiment, thepredator net 46 is shown as being formed out of individual sections 48of netting that are separately attached to the adjacent spar buoys 16.In an alternative embodiment, the net may be formed out of a singlesection of netting. In still other embodiments of the invention, theconnecting lines 34 lines may be integral part of the predator net 46.

Another feature of this invention illustrated in FIG. 2 is the use ofmultiple anchor assemblies for securing the individual spar buoys 16 tothe sea bed. This embodiment of the invention may be practiced when itis desired to place the system 40 in rough waters.

The damper plates 42 of spar buoy pen system 40 reduce the wave-inducedvertical movement of the associated spar buoys 16 and the entire pensystem. This serves to both reduce the danger and lessen the difficultyof operating a vessel in the vicinity of the pen during tendingoperations. Another advantage of reducing the vertical motion of the pensystem is that it reduces the resulting stress and strain levels towhich the connecting components of the system 40 are exposed so as toincrease their useful lifetime.

Still another advantage of this embodiment of the system is that thedamper plates 42 can be selected so that the spar buoys 16 and net pen14 will follow the oscillations of long period underlying waves, calledswells, that are present in most sea states. Tender vessels typicallyoscillate with the swells. Consequentially, in these embodiments of theinvention the motion of the buoys and the pen will be tuned to themotion of the sea and the tender so as to further lessen the difficultyand danger of tending the contents of the net pen 14. Thus, while thedamper plates 42 allow the system 40 to move with the sea and tendervessels, they limit the movement of the system in response to shortperiod waves, called chop, which induce hazardous short periodoscillations. Another advantage of selecting the damper plates to allowlimited vertical motion of the buoys 16 and the net pen 14, is that itreduces the chances that a sea swell can crest over the pen 14 whichcould cause some of the fish therein to be washed out and/or offer themore active fish an opportunity to swim out over the top of the pen.

The predator net 46 limits the extent to which marine life not containedwithin the system can attack or approach the fish contained within thenet pen 14. For example, the predator net prevents marine mammals orother predators from bumping or attacking the net pen 14 which can, overtime, cause a hole to develop in the net pen which would have obviouslyundesirable results. Moreover, by preventing predators from bumping thenet pen 14, the predator net 46 prevents the marine life in the net penfrom being forced out of the net pen by the bumping action. The predatornet 46 also functions as a barrier to prevent floating debris fromdamaging the net pen 14.

As illustrated in FIG. 3 a spar buoy 16 may alternatively be providedwith a set of stacked damper plates 50a, b, c and d. The top most damperplate, damper plate 50a, is secured directly to the base of the sparbuoy 16 by a set of attachment lines 52. The remaining spar damperplates 50b, c, and d are stacked underneath damper plate 50a and isattached to the overlying damper plate by a set of attachment lines 54.A net 56 is shown as being suspended between damper plates 50a and 50b.

An advantage of providing a set of stacked damper plates 50a, b, c and dis that the individual plates multiply the overall damping effect.Consequently, several small stacked damper plates 50a, b, c and d can beused to reduce wave-induced net motion in circumstances where it iseither undesirable or impractical to use a single, large diameter plate.Still another advantage of providing a set of stacked damper plates andthe net 56 between adjacent plates is that it would be possible to growshellfish on the plates. The net 56 can, of course also be used to holdadditional fish, such as fish that serve as food for the fish in the netpen 14.

It is to be appreciated that, while representative embodiments of theinvention have been shown and described, various changes may be madetherein without departing from the spirit and scope of the invention.For instance, the net pen 14 may have a square, triangular or octagonalshape. Furthermore, the net pen 14 may be replaced with a singleflexible wall formed of either netting, fabric, or canvas. In addition,the spar buoy 16 may be used to hold platforms, feeding systems. orstorage containers. Similarly, masts, bird nets and other devices may beattached to the top of each of the buoys 16. Moreover, in someembodiments of the invention, the damper plates 42 or 50a, b, c and dmay be attached to the associated spar buoys 16 by rigid connectorsrather than the flexible attachment lines as is illustrated. Forexample, it may be desirable to affix either a single damper plate 42 ora set of stacked damper plates 50a, b, c and d to the spar buoy by arigid metal rod. Alternatively it may be desirable to form the spar buoy16 so that clamper plate is an integral part thereof. In theseembodiments of the invention, the damper plate, or a set of damperplates, may be built into the individual spar buoys so as to serve astheir base sections.

It should further be understood that the disclosed range of dimensionsand weights for the elements of this invention are merely illustrativeand not limiting. For example, it is foreseeable in versions of thisinvention wherein the system is used to stabilize either surface orsubmerged living or working facilities, the spar buoys 16 can be 300feet long and 30 feet in diameter. Such versions of the invention can beprovided with the appropriately dimensioned damper plates 42. Moreover,it is clear that the spar buoy pen systems of this invention can beprovided with the damper plates 42 and predator net 46 either togetheror separately as may be required by the specific construction of thissystem. Furthermore, it should also be understood that the predator net46 can be used in embodiments of this invention where attachment lines32 of unequal length are connected between the net pen 14 and the sparbuoys 16 in order to provide the buoys with a righting moment.

As will be readily appreciated from the foregoing, the designillustrated herein incorporates the use of spar buoys to shape andanchor net pens used to grow fish for marketing, research or recreation.With the spar buoy anchored to the bottom of the body of water and thenet pen attached to the spar buoy at the top and bottom, or along itsentire draft, the spar buoy fixes the maximum designed depth of the netpen vertically by virtue of its vertical stability. The direction andmagnitude of the anchoring forces acting through the spar buoy and thenet fix the final net pen configuration in length, width, and depth, andmaintain the net pen in a taut condition. The spar buoy net pen systemcan be used in any configuration, with as few as three buoys for atriangular pen, or more buoys arranged in a line may be used to form awall, depending upon the final net pen configuration. A wall of nettingof fabric can also be used as a current "blocker" to reduce current andforces on a downstream pen or object in its "shadow". This use can beindependent of raising fish. In this system, the anchors 18, the sparbuoy 16, and the net pen 14 all form a flexible structure that can beused to hold a variety of marine species for aquacultural, recreationalor research purposes. Furthermore, the spar buoys make it possible touse a more solid, flexible wall such as fabric or canvas because it willnot be affected by .[.current.]. .Iadd.currents .Iaddend.or waves. Thespar buoy net pens may also be arranged in systems of nets that use oneor more spar buoys in common.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A spar buoy pencomprising:a flexible net forming an enclosed pen; at least threeelongated spar buoys adapted to float substantially vertically wherebyeach said spar buoy is attached to said net at at least two verticallyspaced-apart locations so as to maintain a portion of said net adjacentsaid spar buoy in a substantially vertical orientation, and whereby saidspar buoys are attached to said net at locations spaced apart from eachother so that each said spar buoy can float freely relative to said sparbuoys adjacent thereto; separate anchor means attached to each of saidspar buoys, each said anchor means adapted to urge said spar buoyassociated therewith outwards from said net so that said spar buoys areurged away from each other so as to maintain said pen in an open state;and at least two vertically spaced-apart, generally parallel linesextending between adjacent ones of said spar buoys so as to maintainsaid spar buoys in a predetermined configuration upon removal of saidnet.
 2. The spar buoy pen of claim 1, wherein at least one of saidanchor means includes an anchor attached to said associated spar buoy byan anchor line and a float attached to said anchor line by asupplemental line connected between said anchor and said spar buoy tourge said spar buoy away from said net.
 3. The spar buoy pen of claim 1,wherein at least one said spar buoy is connected to said net by a firstupper attachment line and a second upper attachment line, said firstattachment line being shorter than sraid second attachment line so thatsaid spar buoy is displaced from a vertical position at a predeterminedangle.
 4. The spar buoy pen of claim 3, wherein said predetermined angleis in the range of 5° to 25° from the vertical towards said net.
 5. Thespar buoy pen of claim 3, wherein said predetermined angle isapproximately 15° from the vertical towards said net.
 6. The spar buoypen of claim 1, wherein: said net is .[.diminished.]. .Iadd.dimensioned.Iaddend.so that said pen is located within a perimeter of an areadefined by said spar buoys;at least two vertically spaced-apartattachment lines are connected between each of said spar buoys and saidnet; and a predator net is suspended from each of said spar buoys so asto surround said pen wherein said predator net includes said at leasttwo vertically spaced-apart generally parallel lines for maintainingsaid spar buoys in said predetermined configuration.
 7. The spar buoypen of claim 6, wherein said predator net is formed from a plurality ofseparate sections.
 8. The spar buoy of claim 7, wherein each predatornet section is suspended between said adjacent spar buoys.
 9. The sparbuoy .Iadd.pen .Iaddend.of claim 1, further including at least onedamper plate suspended below at least one of said spar buoys.
 10. Thespar buoy pen of claim 1, further including a plurality of damper platessuspended below at least one of said spar buoys.
 11. The spar buoy penof claim 10, further including a net extending between at least two ofsaid damper plates.
 12. A spar buoy pen comprising:a flexible netforming an enclosed pen; at least three elongated spar buoys adapted tofloat substantially vertically attached to said net pen at horizontallyspaced-apart locations so as to suspend said net above a sea bed wherebyat least one of said spar buoys is connected to said net pen by a firstupper attachment line and a second .[.upper.]. .Iadd.lower.Iaddend.attachment line, wherein said first attachment line is shorterthan said second attachment line so that said spar buoy is displacedfrom the vertical position at a predetermined angle; a predator netsuspended from said spar buoys so as to surround said pen; and separateanchor means attached to each of said spar buoys, wherein each saidanchor means is adapted to urge said spar buoy associated therewithoutward so as to maintain both said predator net and said pen in an openstate.
 13. The spar buoy pen of claim 12, wherein said predeterminedangle .[.if.]..Iadd.is .Iaddend.in the range from 5 to 25 degrees fromthe vertical toward said net pen.
 14. The spar buoy pen of claim 12,wherein at least one spar buoy is further provided with a damper platesuspended a distance below said spar buoy.
 15. The spar buoy pen ofclaim 12, further including a plurality of damper plates suspended belowat least one of said spar buoys.
 16. The spar buoy pen of claim 15further including a net extending between at least two of said damperplates. .Iadd.17. A non-rigid structural-frame-free spar buoy pencomprising:a flexible net forming an enclosed pen; at least threeelongated spar buoys adapted to float substantially vertically, eachsaid spar buoy being attached to said net at at least two verticallyspaced-apart locations so that said flexible net is held openvertically, and said spar buoys being attached to said net at locationshorizontally spaced-apart from each other, wherein said spar buoy pendoes not include a rigid structural frame so that each said spar buoycan float freely relative to said spar buoys adjacent thereto; andseparate anchor means attached to each of said spar buoys, each saidanchor means adapted to urge said spar buoy associated therewithoutwards from said net so that said spar buoys are urged away from eachother so that said flexible net is held open horizontally without arigid structural frame. .Iaddend. .Iadd.18. The spar buoy pen of claim17, wherein each said spar buoy is attached to said net by a first upperattachment line and a second lower attachment line, said first upperattachment line being shorter than said second lower attachment line sothat each said spar buoy is displaced from the vertical position at apredetermined angle. .Iaddend. .Iadd.19. The spar buoy pen of claim 18,wherein said predetermined angle is in the range of 5 to 25 degrees fromthe vertical towards said net. .Iaddend. .Iadd.20. The spar buoy pen ofclaim 18, wherein each said spar buoy is linked to an adjacent spar buoyby at least one line so as to maintain said spar buoys in apredetermined configuration upon removal of said net. .Iaddend..Iadd.21. The spar buoy pen of claim 18, wherein adjacent ones of saidspar buoys are interconnected with at least two vertically spaced-apart,generally parallel lines so as to maintain said spar buoys in apredetermined configuration upon removal of said net. .Iaddend..Iadd.22. The spar buoy pen of claim 21, wherein said anchor meansincludes an anchor attached to said associated spar buoy by an anchorline and an auxiliary float attached to said anchor line so as to urgesaid associated spar buoy away from said net. .Iaddend. .Iadd.23. Thespar buoy pen of claim 18, wherein said anchor means includes an anchorattached to said associated spar buoy by an anchor line and an auxiliaryfloat attached to said anchor line so as to urge said associated sparbuoy away from said net. .Iaddend. .Iadd.24. The spar buoy pen of claim17, wherein each said spar buoy is linked to an adjacent spar buoy by atleast one line so as to maintain said spar buoys in a predeterminedconfiguration upon removal of said net. .Iaddend. .Iadd.25. The sparbuoy pen of claim 24, wherein said anchor means includes an anchorattached to said associated spar buoy by an anchor line and an auxiliaryfloat attached to said anchor line so as to urge said associated sparbuoy away from said net. .Iaddend. .Iadd.26. The spar buoy pen of claim17, wherein adjacent ones of said spar buoys are interconnected with atleast two vertically spaced-apart, generally parallel lines so as tomaintain said spar buoys in a predetermined configuration upon removalof said net. .Iaddend. .Iadd.27. The spar buoy pen of claim 17, whereinsaid anchor means includes an anchor attached to said associated sparbuoy by an anchor line and an auxiliary float attached to said anchorline so as to urge said associated spar buoy away from said net..Iaddend.